Various materials such as a film may be deposited onto a substrate like a wafer. The differences in temperature and/or thermal expansion coefficients between the film and the substrate may cause mechanical stress known as film stress. Film stress may cause the wafer to bow as well as induce cracks, voids, hillock formation and film lifting, yield loss and poor reliability issues.
Stress/deflection relationships may be utilized for calculating film stress based on the wafer shape data. However, the accuracies of the existing film stress calculation techniques may be limited because they assume that the shape data is uniform across the entire wafer.